tikz 折线 箭头_LaTeX - 可伸缩箭头

% 图1

\documentclass{article}

\usepackage{amsmath}

\usepackage{tikz}

\usetikzlibrary{calc}

\usetikzlibrary{arrows.meta}

\newcommand\xrightrightarrow[1]{\mathrel{\raisebox{0.4mm}{\!\!

\begin{tikzpicture}[>=stealth]

\node[inner sep=1ex] (a) {$\scriptstyle #1$};

\path[draw,

\path[draw,

\end{tikzpicture}}}}

\begin{document}

$$A\xrightrightarrow{\quad I\quad}g(x)$$

\end{document}

% 图2

\documentclass[border=5pt]{standalone}

\usepackage{tikz}

\usepackage{mathtools}

\usetikzlibrary{arrows}

\usepackage{xparse}

\NewDocumentCommand{\xrightleftarrow}{ O{}O{} }{%

\mathrel{%

\vcenter{

\hbox{%

\begin{tikzpicture}

\node[minimum width=0.75cm,align=center] (a){\text{\vphantom{hg}#1}\\[0.3ex]\vphantom{hg}#2};

\draw[-stealth] ([yshift=0.4ex]a.west) -- ([yshift=0.4ex]a.east);

\draw[stealth-] ([yshift=-0.4ex]a.west) -- ([yshift=-0.4ex]a.east);

\end{tikzpicture}

}

}%

}\!\!%

}

\begin{document}

$A\xrightleftarrow B$ \quad

$C\xrightleftarrow[some text here] D$ \quad

$E\xrightleftarrow[][some text again] F$ \quad

$G\xrightleftarrow[some ght][some text again] H$

\end{document}

symbols-a4.pdf 其它宏包的长箭头